1. Technical Field
This disclosure relates to compositions and apparatus for dispensing two distinct substances. More specifically, this disclosure relates to compositions and apparatus which allow long-term storage and subsequent dispensing of two compositions, to wit, a first composition containing an antibiotic (such as erythromycin or clindamycin) and a second composition containing benzoyl peroxide or, alternatively, a retinoid.
2. Background of Related Art
Acne is a common inflammatory disease of human skin, and concentrates in skin areas where sebaceous glands are largest, most numerous, and most active. In its milder types, it is a more or less superficial disorder which is evidenced by slight, spotty irritations and ordinary skin hygiene is a satisfactory treatment. However, in the more inflammatory types of acne, bacterial invasion of or about the pilosebaceous follicles occurs and pustules, infected cysts and, in extreme cases, canalizing inflamed and infected sacs appear. These lesions may become extensive and leave permanent, disfiguring scars.
Acne is very common by puberty and at least 80% of teenagers are afflicted. The facial eruptions are known to cause such psychic trauma in many adolescents that they find it difficult to make personal adjustments and consequently, withdraw and self-pity occur. The sufferer may be constantly aware of the obvious facial blemishes. For these reasons a medicinal preparation and treatment are of definite benefit and may eliminate the need for psychotherapy.
To reduce the severity of acne, various forms of medication have previously been topically applied to the skin. Antibacterial soaps have been used as well as bactericidal agents such as sulfur and resorcinol. Other topical compositions have separately contained benzoyl peroxide, hexachlorophene, erythromycin or neomycin sulfate. None of these prior preparations has been completely effective.
As disclosed by Klein et al. (U.S. Pat. No. 4,497,794), it was discovered that a mixture on the skin of a peroxide, especially benzoyl peroxide and an antibiotic or antibacterial such as clindamycin, neomycin, sodium sulfacetamide, sulfur, tetracycline or erythromycin is particularly beneficial as they can exert a statistically significant synergistic effect. Peroxides inhibit the formation of free fatty acids in the skin, primarily through inactivation of extracellular lipase (via oxidation) necessary to cleave triglycerides into free fatty acids and glycerol. The antibiotic or antibacterial component reduces the concentration of Corynebacterium acnes (i.e., P. acnes), a normal anaerobic bacteria which is the prime source of the lipase. Instead of the benzoyl peroxide, which is preferred, peroxides such as stabilized hydrogen peroxide and peroxides of organic acids, such as a lauroyl peroxide, may be used.
As disclosed by Klein et al., erythromycin and benzoyl peroxide may be applied to the skin in combination in a preformulated aqueous-alcoholic gel. However, if a mixture is first made up and then applied to the skin, it is best that the mixture be made at the time of application or that the mixture be used within twenty-four hours. The prompt use of a premix is necessary due to the chemical incompatibility of the two active agents. Because of this, it is advisable that the two agents be put in separate vials, bottles or other containers. For example, the Klein et al. patent discloses a kit containing, separately bottled liquid compositions comprising 5% benzoyl peroxide and a solution of erythromycin in ethanol or acetone.
However, separately packaging multiple dosages of the two active ingredients presents a number of disadvantages to the end-user. For example, a unit application dosage of each active must be removed sequentially from each container and absorbed onto an applicator, such as a cotton swab, so that it can be coated onto the skin of the user. This provides opportunities for spillage or over- or under-dosing, which can lead to skin irritation and other side effects. Furthermore, such a multidose system necessarily adds to the costs of packaging, shipping and storage.
A dispensing and applicator system intended to overcome these difficulties is disclosed in U.S. Pat. No. 5,562,642. A dual-pad package is disclosed therein that purportedly can contain, preserve and deliver single unit doses of two or more chemically- or physically-incompatible active ingredients. For example, an antibiotic in combination with a liquid, semi-liquid (cream) or gelled aqueous or non-aqueous vehicle can be absorbed by and retained by the first pad and a second ingredient which is physically- or chemically-incompatible with the antibiotic, such as a peroxide, can be absorbed and retained by the second pad, preferably in combination with the appropriate vehicle.
It would be desirable to provide a means for simultaneously dispensing two active acne treating compounds in aesthetically acceptable vehicles which allow prolonged shelf life for both active compounds and easy mixing just prior to application to the skin.
It has now been discovered that two separate compositions, one containing an antibiotic and one containing benzoyl peroxide can be packaged within and dispensed from a common dispenser. More particularly, a dual dispenser contains i) a first composition that is substantially anhydrous and includes a polar solvent, an antibiotic and a thickening agent selected from the group consisting of acrylic acid polymers and polyacrylamides; and ii) a second composition containing benzoyl peroxide. Preferably, the first and second compositions have viscosities that differ by no greater than 25%. By packaging these two anti-acne active ingredients in this manner, long shelflife and convenient dispensing and application are provided.
In an alternate embodiment, two separate compositions, one containing an antibiotic and one containing a retinoid are packaged within and dispensed from a common dispenser. More particularly, a dual dispenser contains i) a first composition that is substantially anhydrous and includes a polar solvent, an antibiotic and a thickening agent selected from the group consisting of acrylic acid polymers and polyacrylamides; and ii) a second composition that is substantially anhydrous, and includes a polar solvent, a retinoid, and a thickening agent selected from the group consisting of acrylic acid polymers and polyacrylamides.